How does the Calvin cycle function in carbon fixation during photosynthesis?

The Calvin cycle functions in carbon fixation by converting carbon dioxide into organic molecules.

During photosynthesis, plants use energy from sunlight to convert carbon dioxide and water into glucose and oxygen. The Calvin cycle, also known as the light-independent reactions, is the process by which carbon dioxide is converted into organic molecules. This cycle occurs in the stroma of the chloroplasts in plant cells.

The first step of the Calvin cycle is the fixation of carbon dioxide. This occurs when carbon dioxide is combined with a five-carbon sugar called ribulose-1,5-bisphosphate (RuBP) to form a six-carbon molecule. This molecule is then split into two three-carbon molecules called 3-phosphoglycerate (3PG).

The next step is the reduction of 3PG into glyceraldehyde-3-phosphate (G3P). This process requires energy in the form of ATP and electrons from NADPH, which were produced during the light-dependent reactions.

Finally, some of the G3P molecules are used to regenerate RuBP, which is necessary for the cycle to continue. The remaining G3P molecules are used to produce glucose and other organic molecules.

Overall, the Calvin cycle plays a crucial role in carbon fixation during photosynthesis. By converting carbon dioxide into organic molecules, plants are able to store energy and build the complex molecules necessary for growth and survival.